I think for a good deal of individuals they mistake how much effort they put into it prior to their break. So maybe you did it for three years as a teenager, and you went twice a week for an hour and a half. That gives you 468 hours of Taekwondo practice during that time frame.

At the face value, that seems like a rather large amount of time to do anything. However, were you doing cardio drills, weight lifting, stretching, and so forth on your off days? I don't want to belittle anyone's effort, but for myself at least, I can get far more out of a week now that I'm an adult than I was a teenager. In a week, you could easily set the alarm early for 30 minutes each day to get 15 minutes of stretching and cardio before the day begins. It wouldn't be unrealistic to put in an hour of working out into your day either after work. The great thing about Taekwondo is you can stretch and kick while watching tv. ;)

Adding in a compliment of balanced cardio, weight training, and a proper diet can lead to far greater results in a limited time frame than you accomplished as a teen. In a week, you could add an extra 7.5 hours to your work out [assuming you've worked out two times a week already for Taekwondo]. In a single year, you'd be adding 390 hours of effort and growth to your ability to do Taekwondo.

I'm often reminded by a comic from Zen Pencils based on an article from James Rhodes when people bring this [and other similar] notions up. I'd strongly recommend giving it a look.

I'm speaking from experience at the moment. I'm thirty. I hadn't done Taekwondo since I was sixteen, where I was on the cusp of three years of attending. I was about to get my red belt, and I competed regularly in the state competitions where I placed consistently. Life, as it often does, found a way to prevent me from wanting to continue something I was passionate about. When I saw an adorable video of my little nephew break his first board, I couldn't help but get motivated to join him and his mother who had restarted as well. In the past two months I've completely changed my schedule and thus my body to be able to enjoy Taekwondo once more. I've grinded every single day in the gym and in the kitchen to make sure that I'm better than I was the day before. In 60ish days, I've gone from 224 lbs to 189 lbs.

I cannot be I'm speaking from experience at the moment. I'm thirty. I hadn't done Taekwondo since I was sixteen, where I was on the cusp of three years of attending. I was about to get my red belt, and I competed regularly in the state competitions where I placed consistently. When I found out that my little nephew was taking it, I couldn't help but get motivated to do so. In the past two months I've completely changed my schedule and thus my body to be able to enjoy Taekwondo once more. I've grinded every single day in the gym and in the kitchen to make sure that I'm better than I was the day before. In 60ish days, I've gone from 224 lbs to 189 lbs.

If you want something, go out and get it. Find the time that you're wasting, find the dead time where you're just twiddling your thumbs doing nothing, and make use of it.